This invention relates to an apparatus for continuous fluid treatment of advancing strand material such as yarns, tow or film and more particularly relates to the continuous fluid treatment of yarn or tow formed of continuous manmmade fibers.
Fluid treatment processes and apparatus have long been widely used in the processing of continuous strand materials such as yarns, fiber and tow. For example, fluid treatment jets can be used for strand transport, tension control, heat transfer, entangling, bulking or crimping of the strand material. The prior art literature abounds with disclosures of processes and apparatus for performing treatment operations such as those noted above on the continuous strand material.
Important considerations in the design and fabrication of apparatus for the fluid treatment of fiber, yarn and tow include the effectiveness of the processing geometry for the purpose at hand, the materials of construction, the economy of fabrication of the fluid treatment apparatus and the accuracy and repeatability of manufacture and assembly. Apparatus design requirements have most frequently been met using circular cross section bores which can be produced relatively inexpensively with great accuracy and repeatability and with good control of fiber, yarn or tow contact surface characteristics.
However, apparatus designs based upon circular cross section bores suffer the disadvantage that they are difficult to thread up. A free end of the stand must be threaded through the device, which requires either stopping the strand processing apparatus or using an aspirator gun to draw the strand through the bore. Slotted designs have been proposed which provide for threading the strand through the device via a permanently open slot. This allows the strand material to be strung into and through the device without the necessity of having a free end of the strand available. However, while slotted designs are easy to thread, they are capable of maintaining only slightly super atmospheric internal pressure. This significantly restricts the extent of fluid treatment which can be achieved in such designs.
To overcome the above problems, U.S. Pat. No. 3,525,134 proposed a fluid treatment apparatus which was of a closeable construction and which utilized a rectangular cross section bore. However, it is quite difficult and expensive to machine uniform rectangular bores with sharp interior corners and uniform surface characteristics within the narrow confines of the bore. Consequently, there are significant practical and economical limitations to this type of fluid treatment apparatus.
My earlier U.S. Pat. Nos. 3,849,846 and 3,994,056 disclosed a continuous strand fluid treatment apparatus which was readily threadable, enabled control of interior contact surface characteristics, did not suffer an undesirable interior flow disruption, and did not trap or snag running strands. This design utilized a trilaminar sandwich structure comprising a yarn treatment duct having at least one fluid entry port thereto, with the duct being formed by a discontinuous inner lamina between two continuous outer laminae. The individual laminae can be readily manufactured and subjected to surface finishing operations prior to final assembly. Then the individual components can be assembled to form a yarn processing duct of the desired configuration.
While the designs set forth in U.S. Pat. Nos. 3,849,846 and 3,994,056 represented a significant advance over previous designs, some limitations remained. In particular, the trilaminar design of these patents cannot accommodate the complex interior geometry requirements of advanced fluid treatment apparatus, such as that set forth in U.S. Pat. No. 3,852,857. The circular cross section strand treatment duct of the '857 patent undergoes several diametrical changes, including a transition from a relatively small diameter entrance zone to an enlarged crimping chamber which produces pneumatic stuffer box crimping of the strand material. The trilaminar designs of the '846 and '056 patents can accommodate simple one dimensional changes in duct cross section, but one duct cross section dimension must remain constant at the thickness of the discontinuous inner lamina.